sub in stereo system

Discussion in 'Speakers' started by Dan~Z, May 3, 2004.

  1. Dan~Z

    Dan~Z Auditioning

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    hey, i am wanting to put a sub into my stereo system (main unit, two speakers) but the main unit doesn't have a sub out plug. i was wondering if it's alright to put the (powered) sub in using the speaker wires eg. split negative wire off right speaker and positive off left and hook up to positive and negative of sub. i haven't bought a sub yet, i'm waiting to see if its possible. i also want to leave the speakers running of the unit's amp and not mess too much with them. will this type of setup work or not?
     
  2. ChrisBee

    ChrisBee Stunt Coordinator

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    You should make sure you buy an active sub that has high level (speaker type) Input and Output terminals
    (8 terminals in all).

    You then have two options:

    1) You can connect the sub in parallel with the main speakers. You'll need two sets of speaker cables coming from the stereo amplifier speaker terminals. One pair (Left & Right) to reach the sub's Input terminals and another pair of cables to reach the main speakers as usual.
    This is (possibly) the highest sound quality option as the main speakers aren't filtered in any way. The subwoofer merely adds bass weight below the main speakers roll-off point. Ideally the sub's crossover frequency should be set after testing with an SPL meter and test tones for the flattest response.

    2) You can use the active subwoofer's internal crossover. You don't wire from the stereo amp direct to your speakers at all. Instead you connect your stereo amp to the subwoofer high level Input terminals (two cables Left & Right). The stereo speakers are then fed ONLY from the high level subwoofer Output teminals. Again with normal speaker cable (Left & Right). The crossover frequency is usually around 80Hz.
    This option saves the stereo amp and speakers some bass load but the crossover MIGHT spoil the sound quality of your stereo speakers. Depending on the quality of the sub's built-in crossover filter.

    ChrisBee

    My simple website illustrates how I use an SVS sub with my stereo system:

    http://mysite.freeserve.com/svs_pci_music/index.jhtml
     
  3. ChrisWiggles

    ChrisWiggles Producer

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    I would hesitate on #1, I'm not sure if that will work.
     
  4. John Garcia

    John Garcia Executive Producer

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    #1 will work fine, and would be the better choice IMO, but it depends on how good the sub's high pass x-over is as Chris Bee mentions.
     
  5. ChrisBee

    ChrisBee Stunt Coordinator

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    Hi Chris

    What's the problem with option 1? [​IMG]

    It's the way I do it myself. :b

    Perhaps it was the way I put it in my post? [​IMG]

    ChrisBee
     
  6. ChrisWiggles

    ChrisWiggles Producer

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    It would reduce the ohms would it not? I did this with an older sony receiver, and it wouldn't work with this setup, though I've never had the need to try it on another like this. I just have some hesitation about it is all, as I'm unclear as to how that pass-thru works without speakers hooked up.
     
  7. John Garcia

    John Garcia Executive Producer

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    Since the sub is only picking up the signal, it wouldn't be seen as a "load", so it should not affect the impdance. The receiver/amp is not driving the sub. The preferable way would be to run it off a second set of speaker outputs if available. If it were a passive sub, then it could very easily be an impedance issue. That's how I ran the sub in my 2ch system also, but it ended up being WAY too much for my bedroom, so I sold the extra sub.
     
  8. ChrisWiggles

    ChrisWiggles Producer

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    John: that was my original understanding, that the sub wired like that, sort of in parallel, but not really, would pose no extra load at all. However, i had a sony WM20 wired like that to an older sony PL receiver that would go into protect immediately, and I can only assume that it was seeing a 4-ohm load. So now I'm a little confused as to what is going on, since if the output is not looped through a speaker, how would it get any signal at all then? I guess I've always been confused on how this works, and never had the need to figure it out. Maybe someone knows for sure?
     

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